Non-equilibrium plasmas are preferably used for surface treatment in industry. In order to increase efficiency of the surface treatment, a gliding arc may be utilized whereby the power of the plasma may be increased by keeping the non-equilibrium condition, see e.g. A. Fridman et al., “Gliding arc discharge”, Progress in Energy and Combustion Science 25, (1999), pages 211-231.
Existing gliding arcs yield a problem that the advantages of gliding arcs are not effectively used, and thereby the resulting surface treatment effect is insufficient. For example, the extension (or length) of the discharge of prior art gliding arcs is very limited which reduces their applicability for the object with a variety of sizes and shapes.